CUTTING EDGE 4T9561 - Caterpillar

Illustration 1 g02613616
735/740 Articulated Truck Data Link Communication SystemThe ECM uses two different data links for communication the Cat Data Link and CAN Data Link. The systems of data links also allow communication with service tools.The data link is bidirectional. Each ECM can send and receive information. The data link is not a visible component. The data link consists of internal ECM circuits, the related harness wiring, and the harness connectors.The ECM communicate over the two data links that are present on the machine. The two types of systems are listed below.Cat Data Link - The Cat Data Link is used to send information about the status of the system between control modules and the Caterpillar Electronic Technician (ET).CAN Data Link - The CAN Data Link is a high speed data link. The CAN Data Link is used for high speed communication between the ECM and the control modules of other machine systems. Data Link Diagnostics
Both of the data links on the machine are monitored by the ECM for abnormal internal circuit conditions and for external circuit conditions. The ECM will activate diagnostic codes for a specific control module and a circuit in the data link when an abnormal condition is detected.When the ECM detects an abnormal condition in a circuit in the data link, the ECM will activate a "companion" diagnostic code along with the diagnostic code. for the involved control module in order to alert the technician to which data link system is involved. The companion diagnostic codes for the ECM are listed below:CID 0247 - FMI 09 or FMI 14 - SAE J1939 Data LinkCID 0248 - FMI 09 or FMI 14 - Cat Data LinkAn example of how the companion codes are used by the ECM for the data link circuits: The Chassis ECM is communicating with the Transmission/Chassis ECM over the CAN Data Link circuit, however, some expected data is not being communicated. The Chassis ECM will activate the CID 0296 FMI 14 diagnostic code (Special Instruction - not receiving expected information) for the Transmission/Chassis ECM. The Chassis will also activate the CID 0247 - FMI 14 companion diagnostic code (CAN Data Link) in order to indicate which data link circuit is involved. The companion diagnostic code will clear when the primary diagnostic code is cleared.A CID 0247 or a CID 0248 companion diagnostic code will always be activated when any of the following module communication codes is activated by the Chassis ECM.CID 0296 - TransmissionCID 0588 - CMPDCID 0590 - Engine ECM